Interpretive Summary: By invitation, this manuscript was prepared as a contribution to a book entitled: Tidal Salt Marshes of the San Francisco Estuary: Ecology, Restoration, Conservation (A. Palaima, editor) to be published by University of California Press, Berkeley California. The chapter provides analysis of estuarine vegetation at a National Estuarine Research Reserve (NERR) site (Rush Ranch) in the San Francisco Bay Estuary. The NERR reserve system is a federal and state partnership between NOAA, State Parks, State Bay Conservation Commission, San Francisco State University and a local land trust. The data analyses presented quantify vegetation by hydrogeomorphic setting, provide a historic perspective of vegetation change, and highlight the influence of exotic, invasive plant species within the ecological community. The chapter also includes a detailed flora compiled from more than twenty years of field research. The manuscript provides a historic perspective coupled with an ecological framework for future monitoring, research and adaptive conservation management at Rush Ranch and in the greater San Francisco Estuary.

Technical Abstract:
The Rush Ranch Open Space Preserve (Rush Ranch) is a component site of the San Francisco Bay National Estuarine Research Reserve (SF Bay NERR) that includes one of the largest undiked tidal wetlands in the San Francisco Estuary. The brackish tidal wetlands grade into transitional vegetation and undeveloped grasslands of the Potrero Hills, and include diverse vegetation that reflect the estuarine position, land use history, and hydrogeomorphic complexity of the site. Rush Ranch includes 4 major estuarine geomorphic units that are widely distributed in the region and support unique vegetation: subtidal channel beds, fringing tidal marsh, tidal marsh plain and tidal marsh-terrestrial ecotone that are distinguished by small variations in hydrology and elevation. We present data on vegetation within each of these landforms, considering each vegetation community as a function of changing physical environment as well as a mixture of interacting species. This chapter also includes an extensive flora of the estuarine wetlands and associated ecotones. Past land-use and exotic plant species invasions have substantially altered Rush Ranch tidal marsh vegetation patterns. Despite these influences, Rush Ranch’s position in the landscape provides important and increasingly rare habitat linkages between the tidal marsh and upland grasslands, providing great potential for restoration and enhancement.